Strip where clauses from the PowerUp code.

[ZumiKua]

Hi there, thank you for your great library, with it I can finally get my DI framework up and running.

While playing with SuperNode, I found a bug in it, with the following code:

public class MyDisposable : IDisposable {
  public void Dispose() { }
}

[SuperNode(typeof(GenericWithWhereClause<MyDisposable>))]
public partial class TestNode : Node {
  public override partial void _Notification(int what);
}

[PowerUp]
public class GenericWithWhereClause<T> where T : IDisposable {
  public void OnMyPowerUp(int what) { }
}

The generated code will become:

#pragma warning disable
#nullable enable
using System;
using Godot;
using SuperNodes.Types;
  partial class TestNode where global::MyDisposable : IDisposable
  {
    public void OnMyPowerUp(int what)
    {
    }
  }
#nullable disable
#pragma warning restore

Which is definitely not legal C# code.

This PR fix this bug by strip the where clauses from the PowerUp code.

Removing the where clauses in the PowerUp code should not be a problem as the generic parameters of PowerUp are replaced with real type during code generation... am I right?

This is my first time playing with C#'s codegen technology, mistakes may be made, feel free to leave any comments, or you can reject this if you decide to fix this by yourself.

[jolexxa]

This is great, thank you. Generic constraints only need to be specialized by one of the partial implementations.